2. Microsoft

Thirty-two percent of the top 50 U.S. technology companies viewed the software giant as a threat in their annual filings with the SEC. Activision Blizzard and Priceline.com were among the 16 companies that listed Microsoft in the risk factors or competitors section of their 10-K reports.

Microsoft is not just about computer software as it's proven through its investments in the Xbox, which is paying off, and Internet services, which isn't yet. The industry is watching to see who will replace Steve Ballmer as CEO and where Microsoft will go next.